KR102384228B1 - Semiconductor laser resonator and Semiconductor laser device having the same - Google Patents

Abstract

Disclosed is a semiconductor laser resonator that generates laser light by absorbing energy from the outside. A semiconductor laser resonator includes a layer of a gain medium comprising a semiconductor material and comprising at least one protrusion provided to protrude thereon by at least one trench. Here, the laser light may be confined to the inside of at least one of the at least one protrusion as a standing wave.

Description

A semiconductor laser resonator and a semiconductor laser device including the same

To a semiconductor laser, and more particularly, to a semiconductor laser resonator capable of selecting or separating a resonance mode, and a semiconductor laser device including the same.

In a semiconductor laser device, a semiconductor laser resonator is the most essential part for obtaining an optical gain, and the gain medium generally has a circular disk shape or a rectangular parallelepiped shape, and the gain medium is covered with a metal or a dielectric material. However, the number of resonant modes generated in the semiconductor laser resonator having such a structure is large and has a complex shape.

A semiconductor laser resonator capable of selecting or separating a resonance mode and a semiconductor laser device including the same are provided.

In one aspect,

In a semiconductor laser resonator that absorbs energy from the outside to generate laser light,

a gain medium layer comprising a semiconductor material and comprising at least one protrusion provided to protrude thereon by at least one trench;

A semiconductor laser resonator is provided in which the laser light is confined to a standing wave in at least one of the at least one protrusion.

The semiconductor laser resonator may further include a metal layer provided outside the gain medium layer to confine laser light generated from the gain medium layer. The semiconductor laser resonator may further include a buffer layer provided between the gain medium layer and the metal layer to buffer optical loss of laser light generated from the gain medium layer.

The semiconductor laser resonator may further include a dielectric layer provided outside the gain medium layer to constrain laser light generated from the gain medium layer, and having a refractive index different from that of the gain medium layer.

The laser light may also be confined to a lower portion of the gain medium layer.

The gain medium layer may have a cylindrical shape or a rectangular parallelepiped shape. In addition, the trench may include at least one of a linear shape, a circular shape, a polygonal shape, and a ring shape.

The at least one protrusion may include at least one first protrusion disposed along an periphery of the gain medium layer. In addition, the at least one protrusion may further include at least one second protrusion provided inside the at least one first protrusion.

The gain medium layer may include an active layer. The active layer may include at least one of a III-V semiconductor material, a II-VI semiconductor material, and quantum dots. The gain medium layer may further include an upper clad layer provided on an upper surface of the active layer and a lower clad layer provided on a lower surface of the active layer.

The semiconductor laser resonator may further include a first contact layer provided on an upper surface of the gain medium layer and a second contact layer provided on a lower surface of the gain medium layer. Here, the first contact layer may be provided to correspond to the at least one protrusion.

In another aspect,

Board; and

A semiconductor laser resonator that is provided on the substrate and generates laser light by absorbing energy from the outside;

The semiconductor laser resonator,

a gain medium layer comprising semiconductor material and comprising at least one protrusion provided to protrude thereon by at least one trench;

There is provided a semiconductor laser device in which the laser light is constrained as a standing wave in at least one of the at least one protrusion.

The semiconductor laser resonator may further include a metal layer provided outside the gain medium layer to confine laser light generated from the gain medium layer. The semiconductor laser resonator may further include a buffer layer provided between the gain medium layer and the metal layer to buffer optical loss of laser light generated from the gain medium layer.

The semiconductor laser resonator may further include a dielectric layer provided outside the gain medium layer to constrain laser light generated from the gain medium layer, and having a refractive index different from that of the gain medium layer.

The at least one protrusion may include at least one first protrusion disposed along an periphery of the gain medium layer. In addition, the at least one protrusion may further include at least one second protrusion provided inside the at least one first protrusion.

The gain medium layer may include an active layer. The active layer may include at least one of a III-V semiconductor material, a II-VI semiconductor material, and quantum dots. The gain medium layer may further include an upper clad layer provided on an upper surface of the active layer and a lower clad layer provided on a lower surface of the active layer.

The semiconductor laser resonator may further include a first contact layer provided on an upper surface of the gain medium layer and a second contact layer provided on a lower surface of the gain medium layer. The semiconductor laser device may further include a plurality of electrodes electrically connected to the first contact layer and the second contact layer.

According to embodiments, by forming at least one trench in the upper portion of the semiconductor laser resonator, laser light generated from the gain medium layer may be confined as a standing wave inside at least one protrusion defined by the trench. Accordingly, only a desired resonance mode can be selected, and unwanted resonance modes can be removed or separated away from the desired resonance mode. Accordingly, the Q-factor of the laser resonator can also be improved. The selection and/or separation of these resonant modes may be controlled by changing the number, shape, size, or angle of the trenches. In addition, by providing a metal layer or a dielectric layer having a refractive index different from that of the gain medium layer on the outside of the gain medium layer, laser light generated from the gain medium layer can be efficiently restrained.

1 is a perspective view schematically showing a semiconductor laser device according to an exemplary embodiment.
FIG. 2 is a perspective view illustrating the gain medium layer shown in FIG. 1 .
3 is a cross-sectional view taken along line III-III' of FIG. 1 .
4 is a cross-sectional view of a semiconductor laser device according to another exemplary embodiment.
5 is a cross-sectional view of a semiconductor laser device according to another exemplary embodiment.
6 is a cross-sectional view of a semiconductor laser device according to another exemplary embodiment.
7A and 7B show semiconductor laser resonators according to another exemplary embodiment.
8A and 8B show semiconductor laser resonators according to another exemplary embodiment.
9A and 9B show semiconductor laser resonators according to another exemplary embodiment.
10A to 10C show semiconductor laser resonators according to another exemplary embodiment.
11A and 11B show semiconductor laser resonators according to another exemplary embodiment.
12A and 12B show semiconductor laser resonators according to another exemplary embodiment.
13A to 13C are diagrams illustrating a Finite Difference Time Domain (FDTD) simulation modeling structure of a conventional semiconductor laser resonator.
14 is a cross-sectional view illustrating an internal structure of the semiconductor laser resonator shown in FIGS. 13A to 13C.
FIG. 15 shows spectra of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 13A to 13C.
16A to 16G show intensity distributions of electric fields of TE mode laser light generated in the semiconductor laser resonator shown in FIGS. 13A to 13C.
FIG. 17 shows spectra of TM mode laser light generated by the semiconductor laser resonator shown in FIGS. 13A to 13C.
18A to 18D show an FDTD simulation modeling structure of a semiconductor laser resonator according to an exemplary embodiment.
19 is a cross-sectional view illustrating an internal structure of the semiconductor laser resonator shown in FIGS. 18A to 18D.
FIG. 20 shows the spectrum of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 18A to 18D.
21A to 21D show intensity distributions of electric fields of TE mode laser light generated in the semiconductor laser resonator shown in FIGS. 18A to 18D.
FIG. 22 shows the spectrum of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 18A to 18D.
23A and 23B show spectra of TM mode laser light generated by the semiconductor laser resonator shown in FIGS. 18A to 18D.
24A to 24D are diagrams illustrating an FDTD simulation modeling structure of a semiconductor laser resonator according to another exemplary embodiment.
FIG. 25 shows the spectrum of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 24A to 24D.
26A to 26F show intensity distributions of electric fields of TE mode laser light generated in the semiconductor laser resonator shown in FIGS. 24A to 24D.
FIG. 27 shows spectra of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 24A to 24D.
28A and 28B show spectra of TM mode laser light generated by the semiconductor laser resonator shown in FIGS. 24A to 24D.

Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals refer to the same components, and the size or thickness of each component may be exaggerated for clarity of description. Further, when it is described that a predetermined material layer is present on a substrate or another layer, the material layer may exist in direct contact with the substrate or another layer, or another third layer may exist therebetween. In addition, since the materials constituting each layer in the following embodiments are exemplary, other materials may be used.

1 is a perspective view schematically showing a semiconductor laser device according to an exemplary embodiment. And, FIG. 2 is a perspective view illustrating the gain medium layer shown in FIG. 1, and FIG. 3 is a cross-sectional view taken along line III-III' of FIG.

1 to 3 , the semiconductor laser device 100 includes a substrate 110 and a semiconductor laser resonator provided on the substrate 110 . As the substrate 110 , for example, a semiconductor substrate may be used, but the present invention is not limited thereto, and in addition, a substrate made of various materials such as glass may be used. As a specific example, an InP or GaAs substrate may be used as the substrate 110 , but is not limited thereto.

The semiconductor laser resonator may absorb energy from the outside to generate laser light. Such a semiconductor laser resonator may have, for example, a nano size or a micro size, but is not limited thereto. The semiconductor laser resonator may include a gain medium layer 120 that absorbs energy by optical pumping or electrical pumping to generate laser light. The gain medium layer 120 may include an active layer 122 including a semiconductor material. The active layer 122 may include, for example, a III-V semiconductor material or a II-VI semiconductor material. Also, the active layer 122 may include quantum dots. As a specific example, the active layer 122 is InGaAs, It may include, but is not limited to, a plurality of quantum wells (multi-quantum walls) including AlGaAs, InGaAsP, AlGaInP, and the like.

The gain medium layer 120 may further include first and second cladding layers 121 and 123 provided above and below the active layer 122 . The first clad layer 121 is provided on the first surface of the active layer 122 (the upper surface of the active layer 122 in FIG. 3 ), and may include an n-type or p-type semiconductor material. As a specific example, the first cladding layer 121 may include n-type InP or p-type InP, but is not limited thereto. The second cladding layer 123 may be provided on the second surface of the active layer 122 (the lower surface of the active layer 122 in FIG. 3 ). When the first clad layer 121 includes an n-type semiconductor material, the second clad layer 123 may include a p-type semiconductor material. Also, when the first clad layer 121 includes a p-type semiconductor material, the second clad layer 123 may include an n-type semiconductor material. As a specific example, the second cladding layer 123 may include p-type InP or n-type InP, but is not limited thereto.

The gain medium layer 120 may have a cylindrical shape, for example. However, the present invention is not limited thereto, and the gain medium layer 120 may have a rectangular parallelepiped shape or other shapes. In the present embodiment, at least one trench 191 is formed in an upper portion of the gain medium layer 120 to a predetermined depth. At least one protrusion 191 ′ may be defined on the gain medium layer 120 by the trench 191 .

Specifically, referring to FIG. 2 , two trenches 191 are formed on the upper portion of the gain medium layer 120 to a predetermined depth. These trenches 191 may have a line shape and may be formed to cross each other. The trenches 191 may be formed at various depths from the upper surface of the gain medium layer 120 . In FIG. 3 , a case in which the trenches 191 are formed in the first clad layer 121 is exemplarily shown, but the present invention is not limited thereto and the trenches 191 are formed in the first clad layer 121 and the active layer 122 . or may be formed on the first clad layer 121 , the active layer 122 and the second clad layer 123 . Four protrusions 191 ′ may be formed on the upper portion of the gain medium layer 120 by the trenches 191 crossing each other in this way, and these protrusions 191 ′ form the outside of the gain medium layer 120 . It can be arranged in a periodic structure according to the

As described above, since the protrusions 191 ′ formed by the trenches 191 are arranged in a periodic structure on the gain medium layer 120 , the laser light generated from the gain medium layer 120 is generated by the protrusions 191 ′. ) may be constrained as a standing wave inside at least one of. Here, the constraint of the laser light as a standing wave inside the protrusions 191 ′ means that the laser light is confined to a predetermined position inside the protrusions 191 ′ although the intensity may change with time. do. Here, the intensity of the laser light confined inside the protrusions 191 ′ may decrease toward the surface of the protrusions 191 ′. Meanwhile, laser light generated from the gain medium layer 120 may be additionally confined not only to the protrusions 191 ′ provided on the gain medium layer 120 , but also to the lower portion of the gain medium layer 120 .

In this way, as the laser light generated from the gain medium layer 120 is confined as a standing wave inside at least one of the protrusions 191 ′, a resonant mode of a desired wavelength can be easily selected as described later. . In addition, unwanted resonance modes can be removed or a desired resonance mode can be effectively separated from other resonance modes. Accordingly, the Q-factor of the semiconductor laser resonator can also be improved. The selection and/or separation of the resonance mode may be made by at least one of the number, shape and size of the protrusions 191 ′ defined by the trenches 191 and the spacing between the protrusions 120b. Meanwhile, as will be described later, when the metal layer 150 is provided outside the gain medium layer 120 , the laser light generated from the gain medium layer 120 can be more efficiently restrained.

A first contact layer 131 may be provided on the upper surface of the gain medium layer 120 . For example, the first contact layer 131 may be provided on the upper surface of the first clad layer 121 . Here, the first contact layer 131 may be formed to have a shape corresponding to the upper surface of the gain medium layer 120 . Accordingly, the trenches 191 formed on the gain medium layer 120 may also extend to the first contact layer 131 . When the first clad layer 121 includes an n-type semiconductor material, the first contact layer 131 may include an n-type semiconductor material, and when the first clad layer 121 includes a p-type semiconductor material The first contact layer 131 may include a p-type semiconductor material. As a specific example, the first contact layer 131 may include n-type InGaAs or p-type InGaAs, but is not limited thereto. Meanwhile, an electrode (not shown) electrically connected to the first contact layer 131 may be further provided.

A second contact layer 132 may be provided on a lower surface of the second cladding layer 123 . The second contact layer 132 may be provided on the upper surface of the substrate 110 . When the second clad layer 123 includes a p-type semiconductor material, the second contact layer 132 may include a p-type semiconductor material, and when the second clad layer 123 includes an n-type semiconductor material The second contact layer 132 may include an n-type semiconductor material. As a specific example, the second contact layer 132 may include p-type InGaAs or n-type InGaAs, but is not limited thereto. An electrode 160 electrically connected to the second contact layer 132 may be further provided on the substrate 110 . When the second contact layer 132 includes a p-type semiconductor material, the electrode 160 may be a p-type electrode, and when the second contact layer 132 includes an n-type semiconductor material, the electrode 160 is It can be an n-type electrode.

A metal layer 150 may be further provided to cover the gain medium layer 120 and the first contact layer 131 . Here, the metal layer 150 positioned on the first contact layer 131 may be formed to have a shape corresponding to the first contact layer 131 . Accordingly, the trenches 191 formed on the gain medium layer 120 may also extend to the metal layer 150 positioned on the first contact layer 131 . The metal layer 150 is provided outside the gain medium layer 120 and serves to confine the laser light generated from the gain medium layer 120 to the inside of the gain medium layer 120 . The metal layer 150 may include, for example, Ag, Au, Cu, Al, or the like, but this is merely exemplary and may include other various metal materials. The laser light generated from the gain medium layer 120 may be more efficiently confined by the metal layer 150 .

A buffer layer 141 may be further provided between the metal layer 150 and the gain medium layer 120 . For example, the buffer layer 141 may be provided between the side surface of the gain medium layer 120 and the metal layer 150 . The buffer layer 141 serves to buffer optical loss that may occur when the laser light generated from the gain medium layer 120 meets the metal layer 150 . The buffer layer 141 may include a material having a refractive index different from that of the gain medium layer 120 . Specifically, the buffer layer 141 may include a material having a smaller refractive index than that of the gain medium layer 120 . For example, the buffer layer 141 may include, but is not limited to, silicon oxide or silicon nitride. Meanwhile, an insulating layer 142 may be further formed on the substrate 110 to cover the exposed upper surface of the second contact layer 132 .

As described above, in the semiconductor laser device 100 according to the exemplary embodiment, trenches 191 are formed on the semiconductor laser resonator, and protrusions 191 ′ defined by the trenches 191 are provided. By doing so, the laser light generated from the gain medium layer 120 may be confined to the inside of at least one of the protrusions 191 ′ as a standing wave. In this way, when the laser light generated from the gain medium layer 120 is confined as a standing wave in at least one of the protrusions 191 ′ provided on the upper portion of the gain medium layer 120 , the resonance mode of the desired wavelength can be easily achieved. You can choose. In addition, unwanted resonance modes can be removed or a desired resonance mode can be effectively separated from other resonance modes. Accordingly, the Q-factor of the semiconductor laser resonator can also be improved. In addition, when the metal layer 150 is provided on the outside of the gain medium layer 120 , the laser light generated from the gain medium layer 120 can be more efficiently restrained.

4 is a cross-sectional view of a semiconductor laser device according to another exemplary embodiment. The semiconductor laser device 100a shown in FIG. 4 is the semiconductor shown in FIGS. 1 to 3 except that the dielectric material 143 is filled in the trenches 191 formed on the gain medium layer 120 . It is similar to the laser device 100 .

Referring to FIG. 4 , the semiconductor laser device 100a includes a substrate 110 and a semiconductor laser resonator provided on the substrate 110 to absorb energy from the outside to generate laser light. Here, the semiconductor laser resonator includes a gain medium layer 120 , and trenches 191 are formed on the gain medium layer 120 . Here, the inside of the trenches 191 formed on the gain medium layer 120 may be filled with a dielectric material 143 . Here, the dielectric material 143 may include, for example, the same material as that of the buffer layer 141 . In addition, the metal layer 150 may be provided to cover the gain medium layer 120 , the first contact layer 131 , and the dielectric material 143 .

5 is a cross-sectional view of a semiconductor laser device according to another exemplary embodiment. The semiconductor laser device 100b shown in FIG. 5 is the semiconductor laser device shown in FIGS. 1 to 3 except that the inside of the trenches 191 formed on the gain medium layer 120 is filled with the metal layer 150 . It is similar to device 100 .

Referring to FIG. 5 , the semiconductor laser device 100b includes a substrate 110 and a semiconductor laser resonator provided on the substrate 110 to absorb energy from the outside to generate laser light. Here, the semiconductor laser resonator includes a gain medium layer 120 , and trenches 191 are formed on the gain medium layer 120 . In addition, the metal layer may be provided to cover the gain medium layer 120 and the first contact layer 131 . Here, the inside of the trenches 191 formed on the gain medium layer 120 may also be filled with the metal layer 150 .

6 is a cross-sectional view illustrating a semiconductor laser device according to another exemplary embodiment.

Referring to FIG. 6 , the semiconductor laser device 100d includes a substrate 110 and a semiconductor laser resonator provided on the substrate 110 to absorb energy from the outside to generate laser light. Here, the semiconductor laser resonator includes a gain medium layer 120 , and trenches 191 are formed on the gain medium layer 120 .

The first contact layer 131 is provided to cover the upper surface of the gain medium layer 120 , and the dielectric layer 170 is provided to cover the side surface of the gain medium layer 120 . The dielectric layer 170 serves to confine the laser light generated from the gain medium layer 120 . To this end, the dielectric layer 170 may include a material having a refractive index different from that of the gain medium layer 120 . Specifically, the dielectric layer 170 may include a material having a smaller refractive index than that of the gain medium layer 120 . The dielectric layer 170 may include, for example, silicon oxide or silicon nitride, but is not limited thereto.

In the above embodiments, the case in which the two trenches 191 are formed on the gain medium layer 120 has been described, but the number and shape of the trenches 191 formed in the gain medium layer 120 may be variously modified. can

7A and 7B show semiconductor laser resonators according to another exemplary embodiment.

In the semiconductor laser resonator shown in FIG. 7A , the gain medium layer 120 has a cylindrical shape, and one linear trench 192 is formed on the gain medium layer 120 to a predetermined depth. Two protrusions 192 ′ may be defined on the upper portion of the gain medium layer 120 by the linear trench 192 . The first contact layer 131 may be provided on the upper surface of the gain medium layer 120 , that is, the upper surface of the protrusions 192 ′, and the second contact layer 132 on the lower surface of the gain medium layer 120 . ) can be provided.

In the semiconductor laser resonator shown in FIG. 7B , three linear trenches 193 are formed to cross over the gain medium layer 120 having a cylindrical shape. Six protrusions 193 ′ may be defined on the upper portion of the gain medium layer 120 by these trenches 193 .

8A and 8B show semiconductor laser resonators according to another exemplary embodiment.

In the semiconductor laser resonator shown in FIG. 8A , a circular trench 194 is formed at a predetermined depth on the gain medium layer 120 having a cylindrical shape. Here, the circular trench 194 may be located in the center of the gain medium layer, and a protrusion 194 ′ provided to surround the circular trench 194 on the upper portion of the gain medium layer 120 by the trench 194 . can be defined.

In the semiconductor laser resonator shown in FIG. 8B , a ring-shaped trench 195 is formed to a predetermined depth on the gain medium layer 120 having a cylindrical shape. Here, the annular trench 195 may be located in the center of the gain medium layer 120 . On the upper portion of the gain medium layer 120 by the annular trench 195 , a first protrusion 195a ′ provided outside the annular trench 195 and a second protrusion 195b provided inside the annular trench 195 . ') can be defined.

9A and 9B show semiconductor laser resonators according to another exemplary embodiment.

In the semiconductor laser resonator shown in FIG. 9A , linear trenches 196a and a circular trench 196b are formed to a predetermined depth on the gain medium layer having a cylindrical shape. Here, the circular trench 196b may be located in the center of the gain medium layer 120 , and the linear trenches 196a may be formed to be connected to the circular trench 196b. A plurality of protrusions 196' arranged in a periodic structure along the periphery of the gain medium layer 120 are defined on the upper portion of the gain medium layer 120 by the linear trenches 196a and the circular trench 196b. can Meanwhile, although a case in which a plurality of linear trenches 196a are formed is illustrated in FIG. 9A , one linear trench 196a may be formed.

In the semiconductor laser resonator shown in FIG. 9B , linear trenches 197a and annular trench 197b are formed to a predetermined depth on the gain medium layer 120 having a cylindrical shape. Here, the annular trench 197b may be located in the center of the gain medium layer 120 , and the linear trenches 197a may be formed to be connected to the annular trench 197b. A plurality of first protrusions 197a' arranged in a periodic structure along the periphery of the gain medium layer 130 on the upper portion of the gain medium layer 120 by the linear trenches 197a and the annular trench 197b; A second protrusion 197b ′ provided at the center of the gain medium layer 120 may be defined. Meanwhile, although a case in which a plurality of linear trenches 197a are formed is illustrated in FIG. 9B , one linear trench 197a may be formed.

Although the case in which the gain medium layer 120 has a cylindrical shape has been exemplarily described in the above embodiments, the shape of the gain medium layer 120 may be variously modified.

10A to 10C show semiconductor laser resonators according to another exemplary embodiment.

In the semiconductor laser resonator shown in FIG. 10A , the gain medium layer 220 has a rectangular parallelepiped shape. In addition, one linear trench 291 is formed on the upper portion of the gain medium layer 220 to a predetermined depth, and two protrusions 291 ′ are formed on the upper portion of the gain medium layer 220 by the linear trench 291 . ) can be defined. In addition, the first contact layer 231 may be provided on the upper surface of the gain medium layer 220 , that is, the upper surface of the protrusions 291 ′, and the second contact layer 232 on the lower surface of the gain medium layer 220 . ) can be provided.

In the semiconductor laser resonator shown in FIG. 10B , two linear trenches 292 intersecting each other are formed on the upper portion of the gain medium layer 220 having a rectangular parallelepiped shape to a predetermined depth. Four protrusions 292 ′ may be defined on the upper portion of the gain medium layer 220 by the linear trenches 292 .

In the semiconductor laser resonator shown in FIG. 10C , three linear trenches 293 are formed to a predetermined depth on the gain medium layer 220 having a rectangular parallelepiped shape. Here, the two linear trenches 293 may be formed in parallel with each other, and the other linear trench 293 may be formed to intersect the two linear trenches 293 . Six protrusions 293 ′ may be defined on the upper portion of the gain medium layer 220 by the linear trenches 293 .

11A and 11B show semiconductor laser resonators according to another exemplary embodiment.

In the semiconductor laser resonator shown in FIG. 11A , a rectangular trench 294 is formed with a predetermined depth on the gain medium layer 220 having a rectangular parallelepiped shape. Here, the rectangular trench 294 may be located at the center of the gain medium layer 220 , and a protrusion 294 ′ provided to surround the rectangular trench 294 may be defined on the upper portion of the gain medium layer 220 . there is.

In the semiconductor laser resonator shown in FIG. 11B , a rectangular ring shape trench 295 is formed to a predetermined depth on the gain medium layer 220 having a rectangular parallelepiped shape. Here, the rectangular annular trench 295 may be located in the center of the gain medium layer 220 . Accordingly, a first protrusion 295a ′ provided outside the rectangular annular trench 295 and a second protrusion 295b ′ provided inside the rectangular annular trench 295 are defined on the upper portion of the gain medium layer 220 . can be

12A and 12B show semiconductor laser resonators according to another exemplary embodiment.

In the semiconductor laser resonator shown in FIG. 12A , linear trenches 296a and a rectangular trench 296b are formed to a predetermined depth on the gain medium layer 220 having a rectangular parallelepiped shape. Here, the rectangular trench 296b may be located in the center of the gain medium layer 220 , and the linear trenches 296a may be formed to be connected to the rectangular trench 296b. A plurality of protrusions 296' arranged in a periodic structure along the periphery of the gain medium layer 220 are defined on the upper portion of the gain medium layer 220 by the linear trenches 296a and the rectangular trench 296b. can Meanwhile, although a case in which a plurality of linear trenches 296a are formed is illustrated in FIG. 11A , one linear trench 296a may be formed.

In the semiconductor laser resonator shown in FIG. 11B , linear trenches 297a and a rectangular annular trench 297b are formed to a predetermined depth on the gain medium layer 220 having a rectangular parallelepiped shape. Here, the rectangular annular trench 297b may be located in the center of the gain medium layer 220 , and the linear trenches 297a are formed to be connected to the rectangular annular trench 297b. Accordingly, on the upper portion of the gain medium layer 220 , the plurality of first protrusions 297a ′ arranged in a periodic structure along the outer edge of the gain medium layer 220 and the second protrusion provided at the center of the gain medium layer 220 . Two protrusions 297b' may be defined. Meanwhile, although a case in which a plurality of linear trenches 297a are formed is illustrated in FIG. 12B , one linear trench 297a may be formed.

In the above embodiments, the case in which the gain medium layer has a cylindrical or rectangular parallelepiped shape has been described. In addition, the shape of the gain medium layer may be variously modified. In addition, the resonance mode may be controlled by variously changing the number, length, angle, or shape of the trenches formed in the gain medium layer. For example, if the number of trenches is adjusted to an even or odd number, only an even number resonant mode or an odd number resonant mode can occur, so basically the number of all resonances is halved compared to the case where there are no trenches. can be reduced to In addition, mode selection is possible by optimizing the structure of the trench to a desired wavelength and mode, and a mode separation effect can also be expected by separating a desired resonance mode from an undesired resonance mode. Also, the Q-factor of the semiconductor laser resonator may be improved due to the resonance mode confinement effect.

13A to 13C are diagrams illustrating a Finite Difference Time Domain (FDTD) simulation modeling structure of a conventional semiconductor laser resonator.

13A is a perspective view illustrating a state in which the conventional semiconductor laser resonator 30 is surrounded by a SiO ₂ layer 40 and an Ag layer 50, and FIG. 13B is an internal plan view of the structure shown in FIG. 13A. And, FIG. 13C is a cross-sectional view taken along line C-C' of FIG. 13B. 13A to 13B , the SiO ₂ layer 40 surrounds the cylindrical semiconductor laser resonator 30 , and the Ag layer 50 surrounds the SiO ₂ layer 40 .

14 is a cross-sectional view illustrating an internal structure of the semiconductor laser resonator shown in FIGS. 13A to 13C.

Referring to FIG. 14 , a semiconductor laser resonator 30 for modeling a Finite Difference Time Domain (FDTD) simulation includes a gain medium layer 20 and first and It includes second contact layers 31 and 32 . Here, the gain medium layer 20 includes the active layer 22 and first and second cladding layers 21 and 23 provided on the upper and lower surfaces of the active layer 22 , respectively. InGaAs having a refractive index n ₁ of 3.65 was used as the active layer 22, and p-AlGaAs and n-AlGaAs having a refractive index n ₂ of 3.4 as the first and second cladding layers 21 and 23, respectively. was used The active layer 22 generally has a quantum well structure, but has been simplified for simulation. In addition, p-GaAs and n-GaAs having a refractive index n ₃ of 3.65 were used as the first and second contact layers 31 and 32 , respectively. The thickness of the semiconductor laser resonator 30 was 0.276 μm, and the radius thereof was 0.4 μm. In addition, the SiO ₂ layer 40 surrounds the periphery of the semiconductor laser resonator 30 to a thickness of 0.1 μm.

FIG. 15 shows a spectrum of TE mode laser light generated by the semiconductor laser resonator 30 shown in FIGS. 13A to 13C. Specifically, the FFT (Fast Fourier Transform) magnitude of the electric field according to the wavelength of the TE mode laser light is shown in FIG. 15 . And, FIGS. 16A to 16G show intensity distributions of the electric field of the TE mode laser light generated in the semiconductor laser resonator 30 shown in FIGS. 13A to 13C. Specifically, the intensity distributions of the electric field for each wavelength of laser light are respectively shown in FIGS. 16A to 16G . In FIGS. 16A to 16G , a red region indicates a region having a strong electric field strength, and a blue region indicates a region having a weak electric field strength. 15 and 16A to 16G show results obtained through simulation when the magnetic dipole is set in the z direction in the semiconductor laser resonator 30 shown in FIGS. 13A to 13C .

15 and 16A to 16G, in the conventional semiconductor laser resonator 30 shown in FIGS. 13A to 13C, for example, a wavelength of 0.625695 μm (FIG. 16A), a wavelength of 0.681405 μm (FIG. 16B), and a wavelength of 0.803571 μm TE resonance modes such as a wavelength (FIG. 16c), a wavelength of 0.951777 μm (FIG. 16D), a wavelength of 0.967326 μm (FIG. 16E), a wavelength of 1.12164 μm (FIG. 16F), a wavelength of 1.34731 μm (FIG. 16G), etc. may be generated. Here, the TE resonance mode refers to a transverse electric mode expressing the electromagnetic field in the resonator when an electric field is generated perpendicular to the propagation direction of the electromagnetic wave. 15 and 16A to 16G , it can be seen that many TE resonance modes are generated in the conventional semiconductor laser resonator 30 . And, as shown in FIG. 15 , it can be seen that the smaller the wavelength, the more resonance modes are generated, and the larger the wavelength, the wider the interval between the resonance modes.

FIG. 17 shows the spectrum of TM mode laser light generated by the semiconductor laser resonator 30 shown in FIGS. 13A to 13C. 17 shows the results obtained through simulation when the electric dipole is set in the z direction in the semiconductor laser resonator 30 shown in FIGS. 13A to 13C . Here, the TM resonance mode refers to a transverse magnetic resonant mode expressing the electromagnetic field in the resonator when a magnetic field is generated perpendicular to the propagation direction of the electromagnetic wave. As shown in FIG. 17 , it can be seen that many TM resonance modes are generated in the conventional semiconductor laser resonator 30 .

As such, since many resonance modes are generated in the conventional semiconductor laser resonator 30 shown in FIGS. 13A to 13C , it is difficult to easily select a resonance mode of a desired wavelength from among the many resonance modes.

18A to 18D show an FDTD simulation modeling structure of a semiconductor laser resonator according to an exemplary embodiment.

18A is a perspective view illustrating a state in which a semiconductor laser resonator 330 is surrounded by an SiO ₂ layer 340 and an Ag layer 350 according to an exemplary embodiment, and FIG. 18B is an inner plan view of the structure shown in FIG. 18A. will show 18C is a cross-sectional view taken along line C-C' of FIG. 18B, and FIG. 18D is a cross-sectional view taken along line D-D' of FIG. 18B. 18A to 18D , the semiconductor laser resonator 330 has a cylindrical shape, and one trench 391 is formed in the upper portion of the semiconductor laser resonator 330 . In addition, the SiO ₂ layer 340 surrounds the semiconductor laser resonator 330 , and the Ag layer 350 surrounds the SiO ₂ layer 340 .

19 is a cross-sectional view illustrating an internal structure of the semiconductor laser resonator shown in FIGS. 18A to 18D. The cross-sectional view shown in FIG. 19 is the same as the cross-sectional view shown in FIG. 14 except that one trench 391 is formed in the upper portion of the semiconductor laser resonator 330 .

Referring to FIG. 19 , the semiconductor laser resonator 330 includes a gain medium layer 320 and first and second contact layers 331 and 332 respectively provided on the upper and lower surfaces of the gain medium layer 320 . Here, the gain medium layer 320 includes an active layer 322 and first and second cladding layers 321 and 323 respectively provided on the upper and lower surfaces of the active layer 322 . In addition, a linear trench 391 is formed in an upper portion of the semiconductor laser resonator 330 to a predetermined depth d. The trench 391 is filled with a SiO ₂ layer 340 .

FIG. 20 shows the spectrum of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 18A to 18D. Specifically, the FFT magnitude of the electric field according to the wavelength of the TE mode laser light is shown in FIG. 20 . And, FIGS. 21A to 21D show intensity distributions of electric fields of TE mode laser light generated in the semiconductor laser resonator shown in FIGS. 18A to 18D . Specifically, the intensity distributions of the electric field for each wavelength of laser light are respectively shown in FIGS. 21A to 21D . In FIGS. 21A to 21D , a red region indicates a region with a strong electric field strength, and a blue region indicates a region with a weak electric field strength. 20 and 21A to 21D show simulations when the depth d of the trench 391 in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D is 0.138 μm and the magnetic dipole is set in the z direction. The results obtained through

20 and 21A to 21D , in the semiconductor laser resonator 330 including one trench 391 illustrated in FIGS. 18A to 18D , for example, a wavelength of 0.674056 μm ( FIG. 21A ) and a wavelength of 0.796742 μm (FIG. 21B), 0.960717 μm wavelength (FIG. 21C), 1.10511 μm wavelength (FIG. 21D), etc. TE resonance modes can be generated. As such, in the semiconductor laser resonator 330 including one trench 391 , the resonance modes are changed compared to the conventional semiconductor laser resonator 30 shown in FIGS. 13A to 13C . For example, the resonance wavelength or resonance intensity may change, and in some cases, a specific resonance mode may disappear. This is because the semiconductor laser resonator 330 shown in FIGS. 18A to 18D includes one trench 391, so the even resonance mode disappears, and also due to a change in boundary condition due to the trench 391. This is because the resonance modes change.

Specifically, comparing FIGS. 15 and 20 , a TE resonance mode of a wavelength of 1.34731 μm, a TE resonance mode of a wavelength of 0.951777 μm, and a TE of a wavelength of 0.625695 μm generated in the conventional semiconductor laser resonator 30 shown in FIGS. 13A to 13C . Since the resonance mode is not suitable for the trench structure, it disappears in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D . On the other hand, the TE resonance mode with a wavelength of 1.12164 μm generated in the conventional semiconductor laser resonator 30 has a spectrum of 1.10511 μm while the resonance wavelength is slightly shifted in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D . size becomes larger. In this way, the resonance characteristics can be changed by forming the trench 391 in the semiconductor laser resonator 330, and accordingly, the desired resonance mode is left alone and the unwanted surrounding resonance mode is removed, or it can be moved away from the desired resonance mode. there is.

FIG. 22 shows the spectrum of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 18A to 18D. Specifically, FIG. 22 shows the results obtained through simulation when the depth d of the trench 391 is 0.06 μm in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D .

It can be seen that the spectrum of the TE mode laser light shown in FIG. 22 is different from the spectrum of the TE mode laser light shown in FIG. 20 in the wavelength or size of the TE resonance modes. This difference is caused by changing the depth of the trench 391 from 0.138 μm to 0.06 μm in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D . In this way, the TE resonance modes can be adjusted by changing the depth of the trench 391 in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D .

23A and 23B show spectra of TM mode laser light generated by the semiconductor laser resonator shown in FIGS. 18A to 18D. 23A shows the results obtained through simulation when the depth (d) of the trench 391 is 0.138 μm and the electric dipole is set in the z direction in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D. there is. And, in FIG. 23B, the depth (d) of the trench 391 in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D is 0.06 μm, and the results obtained through simulation when the electric dipole is set in the z direction are shown. is shown.

Comparing FIGS. 17 and 23A , the TM resonance modes generated in the conventional semiconductor laser resonator 30 and the TM resonance modes generated in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D show a large change in wavelength. However, it can be seen that the size of the spectrum is different. Also, comparing FIGS. 23A and 23B , in the semiconductor laser resonator 330 shown in FIGS. 18A to 18D , as the depth d of the trench 391 is changed, the TM resonance modes and the magnitude of the spectrum It can be seen that changes

24A to 24D are diagrams illustrating an FDTD simulation modeling structure of a semiconductor laser resonator according to another exemplary embodiment.

24A is a perspective view illustrating a state in which a semiconductor laser resonator 430 is surrounded by a SiO ₂ layer 440 and an Ag layer 450 according to another exemplary embodiment, and FIG. 24B is the interior of the structure shown in FIG. 24A It shows a flat surface. 24C is a cross-sectional view taken along line C-C' of FIG. 24B, and FIG. 24D is a cross-sectional view taken along line D-D' of FIG. 24B. 24A to 24D , two linear trenches 491 crossing each other are formed in the upper portion of the cylindrical semiconductor laser resonator 430 . In addition, the SiO ₂ layer 440 surrounds the semiconductor laser resonator 430 , and the Ag layer 450 surrounds the SiO ₂ layer 440 . The cross section of the semiconductor laser resonator 430 shown in FIGS. 24A to 24D is the semiconductor laser resonator 330 shown in FIG. 19 except that two trenches 491 are formed in the upper portion of the semiconductor laser resonator 430 . ) is the same as the cross-sectional view.

FIG. 25 shows the spectrum of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 24A to 24D. Specifically, the FFT magnitude of the electric field according to the wavelength of the TE mode laser light is shown in FIG. 25 . And, FIGS. 26A to 26F show intensity distributions of electric fields of TE mode laser light generated in the semiconductor laser resonator shown in FIGS. 24A to 24D. Specifically, the intensity distributions of the electric field for each wavelength of laser light are respectively illustrated in FIGS. 26A to 26F . In FIGS. 26A to 26F , a red region indicates a region with a strong electric field strength, and a blue region indicates a region with a weak electric field strength. 25 and 26A to 26F, the depth of the trenches 491 in the semiconductor laser resonator 430 shown in FIGS. 24A to 24D is 0.138 μm and the magnetic dipole is set in the z direction. Results are shown.

25 and 26A to 26F , in the semiconductor laser resonator 430 shown in FIGS. 24A to 24D , for example, a wavelength of 0.616438 μm ( FIG. 26A ), a wavelength of 0.665287 μm ( FIG. 26B ), and a wavelength of 0.72208 μm ( 26c), 0.947767 μm wavelength ( FIG. 26d ), 1.06032 μm wavelength ( FIG. 26e ), 1.29162 μm wavelength ( FIG. 26f ), etc. TE resonance modes may be generated. As such, in the semiconductor laser resonator 430 including two trenches 491 , the change in the TE resonance mode is more severe than in the semiconductor laser resonator 330 including one trench 391 . That is, the wavelength of the TE resonance mode is severely shifted, and a new TE resonance mode (for example, a resonance board having a wavelength of 1.06032 μm) that has not appeared in the conventional semiconductor laser resonator 30 appears. On the other hand, the TE resonance mode with a wavelength of 0.947767 μm has less change in the resonance mode compared to other resonance modes. This indicates that the resonance characteristics of the TE resonance mode of the 0.947767 μm wavelength are not significantly affected by the change in the depth of the two trenches 491 . As such, in the semiconductor laser resonator 430 including the two trenches 491, a desired TE resonant mode is easily selected, and other undesired surrounding TE resonant modes are removed or moved away from the desired TE resonant mode. It can be seen that

FIG. 27 shows spectra of TE mode laser light generated by the semiconductor laser resonator shown in FIGS. 24A to 24D. Specifically, FIG. 27 shows a result obtained through simulation when the depth of the trenches 491 in the semiconductor laser resonator 430 shown in FIGS. 24A to 24D is 0.06 μm.

It can be seen that the spectrum of the TE mode laser light shown in FIG. 27 is different from the spectrum of the TE mode laser light shown in FIG. 25 in the wavelength or size of the TE resonance modes. This difference is generated by changing the depth of the trenches 491 from 0.138 μm to 0.06 μm in the semiconductor laser resonator 430 shown in FIGS. 24A to 24D . In this way, the TE resonance modes can be adjusted by changing the depth of the trenches 491 in the semiconductor laser resonator 430 shown in FIGS. 24A to 24D .

28A and 28B show spectra of TM mode laser light generated by the semiconductor laser resonator shown in FIGS. 24A to 24D. 28A shows the results obtained through simulation when the depth of the trenches 491 is 0.138 μm and the electric dipole is set in the z direction in the semiconductor laser resonator 430 shown in FIGS. 24A to 24D . And, in FIG. 28B, the results obtained through simulation are shown when the depth of the trenches 491 in the semiconductor laser resonator 430 shown in FIGS. 24A to 24D is 0.06 μm and the electric dipole is set in the z direction. there is.

Comparing FIGS. 17 and 28A , TM resonance modes generated in the conventional semiconductor laser resonator 30 and the semiconductor laser resonator 430 including two trenches 491 shown in FIGS. 24A to 24D are generated. In the TM resonance modes, it can be seen that the wavelength or spectrum size of the resonance mode is changed. In addition, comparing FIGS. 28A and 28B , it can be seen that the TM resonance modes and the size of the spectrum change as the depth of the two trenches 491 is changed in the semiconductor laser resonator 430 shown in FIGS. 24A to 24D . Able to know.

As described above, by forming at least one trench in the upper portion of the semiconductor laser resonator, it is possible to confine the laser light generated from the gain medium layer as a standing wave in the protrusions defined by the trench. Here, the resonance modes may be adjusted by changing the number, length, angle, or shape of the trenches. By optimizing the structure of the trench to a desired wavelength and mode, mode selection is possible, and a mode separation effect can also be expected by separating a desired resonance mode from an unwanted resonance mode. Also, the Q-factor of the semiconductor laser resonator may be improved due to the resonance mode confinement effect.

According to the above exemplary embodiments, the semiconductor laser resonator may be operated in a desired resonance mode at a desired wavelength by forming at least one trench on the gain medium layer in the nano-sized or micro-sized semiconductor laser resonator. In addition, the resonance mode may be selectively separated by removing the unwanted surrounding resonance mode or moving the desired resonance mode away from the unwanted surrounding resonance mode. In addition, only a desired resonance mode may selectively enhance its intensity. The TE resonance mode or the TM resonance mode may be controlled by adjusting the shape, number, length, direction, or angle of the trenches formed in the gain medium layer. By providing a metal layer or a dielectric layer having a refractive index different from that of the gain medium layer on the outside of the gain medium layer, it is possible to efficiently confine the laser light generated from the gain medium layer. A nanoscale semiconductor laser resonator including such a trench may be manufactured by using, for example, electron beam lithography, FIB (Focused Ion Beam), or KrF type photolithography by using sophisticated patterning.

As described above, the semiconductor laser resonator with easy control of the resonance mode can be applied to various fields. For example, by implementing the light source as a nano laser resonator, it is possible to manufacture an on-chip photonic IC (on-chip photonic IC) that is ultra-fast, low-power, and miniaturized. In addition, when the nano laser resonator is used as an optical signal transmission means, high-speed data transmission is possible, and an optical TSV (Through-Silicon Via) that can transmit signals at high speed and solve the heat problem can be realized. Also, the nano laser resonator can be applied as a high-precision and high-speed optical clock source compatible with CMOS.

100,100a,100b,100c.. semiconductor laser device
110. Substrate
120,220,320.. gain medium layer
121,221,321.. first cladding layer
122,222,322.. active layer
123,223,323.. second cladding layer
131,231,331.. first contact layer
132,232,332.. second contact layer
141. Buffer Layer
142. Insulation layer
150.. metal layer
160. Electrodes
170. Dielectric layer
191,192,193,194,195,196a,196b,197a,197b.. Trench
291,292,293,294,295,296a,296b,297a,297b.. Trench
191',192',193',194',195a',195b',196',197a',197b'..
291',292',293',294',295a',295b',296',297a',297b'..

Claims (26)

In a semiconductor laser resonator that absorbs energy from the outside to generate laser light,
a gain medium layer comprising a semiconductor material and comprising at least one protrusion provided to protrude thereon by at least one trench;
The at least one trench is formed in an upper portion of the gain medium layer to be connected to each other while being symmetrically formed with respect to a center of the gain medium layer,
A semiconductor laser resonator in which the laser light is confined to a standing wave in at least one of the at least one protrusion. The method of claim 1,
The semiconductor laser resonator further comprising a metal layer provided outside the gain medium layer to confine the laser light generated from the gain medium layer. 3. The method of claim 2,
and a buffer layer provided between the gain medium layer and the metal layer to buffer optical loss of laser light generated in the gain medium layer. The method of claim 1,
and a dielectric layer provided outside the gain medium layer to constrain laser light generated from the gain medium layer and having a refractive index different from that of the gain medium layer. The method of claim 1,
A semiconductor laser resonator in which the laser light is also confined to a lower portion of the gain medium layer. The method of claim 1,
The gain medium layer is a semiconductor laser resonator comprising a cylindrical shape or a rectangular parallelepiped shape. The method of claim 1,
The trench includes at least one of a planar shape of a linear shape, a circular shape, a polygonal shape, and a ring shape. The method of claim 1,
and the at least one protrusion includes at least one first protrusion disposed along an outer periphery of the gain medium layer. 9. The method of claim 8,
The at least one protrusion further includes at least one second protrusion provided inside the at least one first protrusion. The method of claim 1,
wherein the gain medium layer includes an active layer. 11. The method of claim 10,
The active layer is a semiconductor laser resonator comprising at least one of a III-V semiconductor material, a II-VI semiconductor material, and quantum dots. 11. The method of claim 10,
The gain medium layer may further include an upper clad layer provided on an upper surface of the active layer and a lower clad layer provided on a lower surface of the active layer. The method of claim 1,
The semiconductor laser resonator further comprising a first contact layer provided on an upper surface of the gain medium layer and a second contact layer provided on a lower surface of the gain medium layer. 14. The method of claim 13,
The first contact layer is provided to correspond to the at least one protrusion. Board; and
A semiconductor laser resonator that is provided on the substrate and generates laser light by absorbing energy from the outside;
The semiconductor laser resonator,
a gain medium layer comprising semiconductor material and comprising at least one protrusion provided to protrude thereon by at least one trench;
The at least one trench is formed in an upper portion of the gain medium layer to be connected to each other while being symmetrically formed with respect to a center of the gain medium layer,
A semiconductor laser device in which the laser light is confined as a standing wave in at least one of the at least one protrusion. 16. The method of claim 15,
The semiconductor laser resonator may further include a metal layer provided outside the gain medium layer to confine laser light generated from the gain medium layer. 17. The method of claim 16,
The semiconductor laser resonator further includes a buffer layer provided between the gain medium layer and the metal layer to buffer optical loss of laser light generated in the gain medium layer. 16. The method of claim 15,
The semiconductor laser resonator further includes a dielectric layer provided outside the gain medium layer to constrain laser light generated from the gain medium layer, and having a refractive index different from that of the gain medium layer. 16. The method of claim 15,
The trench is a semiconductor laser device comprising at least one of a planar shape of a linear shape, a circular shape, a polygonal shape, and an annular shape. 16. The method of claim 15,
The at least one protrusion includes at least one first protrusion disposed along an outer periphery of the gain medium layer. 21. The method of claim 20,
The at least one protrusion further includes at least one second protrusion provided inside the at least one first protrusion. 16. The method of claim 15,
wherein the gain medium layer includes an active layer. 23. The method of claim 22,
The active layer is a semiconductor laser device comprising at least one of a III-V semiconductor material, a II-VI semiconductor material, and quantum dots. 23. The method of claim 22,
The gain medium layer may further include an upper clad layer provided on an upper surface of the active layer and a lower clad layer provided on a lower surface of the active layer. 16. The method of claim 15,
The semiconductor laser resonator may further include a first contact layer provided on an upper surface of the gain medium layer and a second contact layer provided on a lower surface of the gain medium layer. 26. The method of claim 25,
The semiconductor laser device further comprising a plurality of electrodes electrically connected to the first contact layer and the second contact layer.

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